A semiconductor laser constructed by a prior art construction method is shown in FIG. 2. In FIG. 2, the reference numeral 1 designates a circular attachment plate to which a semiconductor laser chip and a SPD (sensitive photo diode) chip are mounted. The reference numeral 2 designates a cathode terminal for a semiconductor laser chip, and the reference numeral 3 designates an anode terminal for a SPD. The reference numeral 4 designates a Kovar cap having a laser light transparent window 5, and this cap 4 is welded to the circular attachment plate 1 by ring projection welding. The reference numeral 6 designates an iron block stem which is gilded. The this block stem 6 is provided on the circular attachment plate 1 contained in the inside of the cap 4. The reference numeral 7 designates a semiconductor laser chip mounted on the block stem 6 via the silicon submount 8. The reference numeral 9 designates a monitoring SPD chip fixed at a predetermined position on the attachment plate 1 in the neighborhood of the semiconductor laser chip 7. The attachment surface for the SPD chip 9 is a surface inclined relative to the attachment plate 1 so that reflected light is not incident on the semiconductor laser chip 7. The reference numeral 10 designates a lens attached to the window 5 of the cap 4. The reference numeral 11 designates wires such as gold wires for connecting the semiconductor semicondrctor laser chip 7 to the cathode terminal 2 and the SPD chip 9 to the anode terminal 3. The reference numeral 12 designates an anode terminal for the laser chip 7.
A method of constructing a semiconductor laser of such a construction will be described in the following.
At first, a block stem 6 is fixed onto a predetermined position of the attachment plate 1. Next, a semiconductor laser chip 7 is fixed onto the block stem 6 via the silicon submount 8, and the SPD chip 9 is mounted onto the attachment surface for SPD. Thereafter, the semiconductor laser chip 7 and the cathode terminal 2, and the SPD chip 9 and the anode terminal 3, are respectively connected by wires 11. Then, the cap 4 is fixed onto the attachment plate 1 by ring projection welding to seal the semiconductor laser chip 7, the SPD chip 9, and the like.
In this way, a semiconductor laser is constructed.
In such a prior art construction method of a semiconductor laser, however, there were drawbacks in that the construction work is complicated as well as expensive since the block stem 6, the cathode terminal 2, and the anode terminal 3 are separate parts, the respective bonding surfaces are positioned in different planes, and the cap 4 is fixed to the attachment plate 1 by the ring projection welding.